Method for cracking liquid hydrocarbons in an electrical discharge



Jan.l20, 1970 A wATARU lsHlBAs'Hl 3,491,010

METHOD FOR CRACKING LIQUID HYDROCARBONS IN AN ELECTRICAL DISCHARGE Filed May 18, 1965 INVENTQR. Watoru Ishlbosh-l ATTORNEY United States Patent O U.S. Cl. 204-171 7 Claims ABSTRACT OF THE DISCLOSURE A process for cracking liquefied hydrocarbon materials into gaseous components by spark discharge comprising the steps of: producing a mixture of liquefied hydrocar- ,bon material with microiine carbon particles; containing said mixture in a reactor, equipped with a pair of electrodes; subjecting said mixture in said reactor to a pulsating current between the electrodes of a voltage sufficient to eifect spark discharges among the carbon particles occurring with an accompanying noise and prior to the application of said current interposing the step of presetting said gap between said electrodes to prevent arc discharges when said pulsating current is applied.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a method for cracking liquid hydrocarbon materials. More particularly, the invention relates to a method for cracking liquid hydrocarbons into their gaseous components by means of spark discharge. To be more particular, the invention is characterized in that microine carbon powderis added to liquid hydrocarbon material in a reaction vessel containing a pair of electrodes which are to be energized with a pulsating current so that a series of spark discharges may take place among the individual carbon particles coming into contact with each other in random and ever-shifting patterns by virtue of the agitation or iiuidization to be effected in the way to be hereinafter explained so that the starting material liquid hydrocarbon may be cracked by the energy of said spark discharge into its gaseous components.

DESCRIPTION OF THE PRIOR ART It has recently been generally known that electro-chemical reactions may be carried out at relatively low temperature by means of the so-called fluidized carbon-spark discharge system which comprises feeding a pulsating current to a pair of electrodes immersed in uidized carbon powder being constantly agitated so as to induce spark discharges among the carb-on particles and, accordingly subject the fluid to the desired chemical reaction.

SUMMARY OF THE INVENTION In accordance with the present invention, a microfine carbon powder is added to a liquid hydrocarbon material and a pulsating current is supplied to a pair of electrodes immersed in the hydrocarbon material. Upon energization of the electrodes, a series of spark discharges occur among the iluidized carbon particles and the starting material hydrocarbon is cracked into its gaseous components.

A primary object of the present invention s to provide a novel method for cracking liquid hydrocarbon materials. Other objects and advantages of the invention will become apparent as the following description proceeds, reference being had to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional elevation of an experimental apparatus for use in the cracking method of this invention, and

FIG. 2 is an industrial 'but simplified version of the apparatus for use in carrying the present invention into practice.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring, now, to FIG. 1, an enclosed vessel or cracking tower 1 has a roof 2 provided with a central gas collector 3. In the vessel 1 is disposed a pair of iron electrodes 4 and 5, the upper ends of which are connected t0 a pulsating current source 7 outside through conductors 6 and 6', respectively. The gap between the electrodes 4 and 5 depends on the peak voltage of the pulsating current to be supplied. However, in order that no arc discharge may take place, it preferably ranges from 50 mm. to 150 mm. The pulsating current source 7 is capable of generating a pulsating current of about 10,000 volts and 20 to 100 kilocycles per second.

A liquid hydrocarbon material A, e.g. heavy oil, is put in the vessel 1 to such a level that the electrodes 4 and 5 are at least partially submerged. In this arrangement, if a pulsating current of e.g. 60 kc./s. were supplied to the electrodes 4 and 5, there would be no change in the state of affairs because of the presence of heavy oil which is an electrically insulating substance. However, when microfine carbon particles of about 0.1 to 0.01 millimeter in diameter are added to the heavy oil in the ratio of about grams of carbon to 1000 liters o-f heavy oil, there is heard a sustained muled sound for a few seconds and, then, the carbon particles begin to emit loud sounds of discharge. The gases being evolved in this manner is collected by means of said gas collector 3. In experiment using the apparatus described above, the following results were obtained (see Table 1). In the table, all percentages are by weight.

TABLE 1 51. 0 02H4 7. 4 6. 1 C4Ha 19. 9 5. 6 02H5 I 2. 4 0. 5 H2 7. 5

The cracking of heavy oil A by spark discharge described hereinbefore continues with increasing vivacity until the entire heavy oil apparently, though actually does not assume a boiling state and, consequently, it is progressively cracked. The decrease in volume of the heavy oil is quite apparent and in the above-mentioned experiment, about 15 liters of gases were collected per minute. It is to be noted that throughout the reaction, the liquid temperature in the vessel remains somewhere between 20 C. and 60 C.

The reaction may be discontinued instantly by cutting off the pulsating current supply. At this moment, the residual liquid in the vessel appears blackish because of the presence of great amounts of microfine carbon particles.

The amount of carbon is found to have been increased at the rate of 3 percent each 10 minutes (this rate is an average of the increases observed in a two hours reaction) and the average size of the carbon particles has decreased to 0.05 to 0.10 micron.

While the mechanism involved in the present method described hereinbefore remain yet to be fully elucidated, it may presumably be explained as follows.

Thus, the fine carbon powder is charged to a high potential in heavy oil A when the electrodes submerged therein are supplied with a pulsating current and the charged carbon particles act as intermediate migratory electrodes, so to speak. As a result, there aries a spark discharge between the adjacent carbon particles coming into random and ever-shifting contact when the electrical resistance of the interfacial film of said heavy oil A is overcomei At this moment, there is released a great energy of discharge which cracks the heavy oil A and, at the same time, its impact further agitates the carbon particles. The carbon which has been more nely divided by said discharge and the ne powdery carbon that separates out upon decomposition of the hydrocarbon material allows further spark discharges and cracking to take place so that the heavy oil A is continuously cracked. As has been explained hereinbefore, the cracking method of the present invention utilizes a pulsating current instead of an alternating or a direct current.

A pulsating current is used in the present method to create a high potential gradient between any adjacent carbon particles coming into random and ever-shifting contact with each other through the intermediary of an insulating hydrocarbon film, thereby facilitating the occurence of spark discharge in liquid hydrocarbon.

Stated differently, no joule heat, nor the heat of arc discharge, is expected in the present method. Thus, the cracking of liquid hydrocarbon by the present method is not comparable to the conventional thermal cracking, but depends on the great electrical energy that is released by spark discharge. This conclusion is supported by the observation that the liquid temperature remains somewhere between about 20 and 60 C. throughout the reaction and also by the composition of the gas obtainable in the present method. Thus, according to the cracking method of this invention, a great amount of C2H2 is obtained, whereas the amount of H2 is relatively small. It is to be understood that while heavy oil was used in the experiment described hereinbefore, substantially similar results are also obtained when other types of liquid hydrocarbon materials are employed.

Referring, now, to FIG. 2, which shows the simplest possible apparatus adapted to carry the present invention into practice, a vertical vessel 8 is constricted toward its bottom 9, which is fitted with a bottom plate 10 having a number of small orifices. A pair of electrodes 11 and 12 is disposed within the vessel 8. The electrodes 11 and 12 are carbon rods. 'Ihe constricted bottom 9 is connected to a pipe 13, which in turn is connected to the outlet of a filter 15 through a pump 14. Through the lateral wall of said vessel 9 above the electrodes is provided a circulating pipe 16 which is connected to the inlet of said filter 15. The top of the cracking vessel 8 is covered with a roof structure 18 having a gas collector 17. Outside of the lateral wall of the cracking vessel 8, the bases of said electrodes 11 and 12 are connected to a pulsating current source 20 through conductors 19 and 19', respectively. The pulsating current source 20 is capable of generating a pulsating current of about 3,000i to 100,000 volts and about 20 to 100 kilocycles per second. The filter 15 has a starting material inlet 21 at the top and a carbon powder eliminator (not shown) inside. In operation, a suspension of small amounts of carbon powder in a liquid hydrocarbon material t0 be cracked is admitted through the ,inlet 21. and then, the pump 14 is driven to 4 force the liquid into the cracking vessel 8 through the bottom plate 10. Now, when a pulsating current is supplied to the electrodes, the carbon particles fiuidized in the liquid hydrocarbon material come into random and ever-shifting contact with each other, whereupon spark discharges take place to decompose the hydrocarbon material into its gaseous components. These gases are collected through the gas collector 17, while excess liquid hydrocarbon material overflow into the lter 15 through the circulating pipe 16. As the cracking process proceeds, there is a marked reduction in volume of the liquid hydrocarbon material, and to compensate for this descrade, a fresh supply of hydrocarbon material is fed through the lter 15. It should be noticed that said fresh supply of hydrocarbon material need not contain carbon particles, for as has been explained above, the supply of carbon in the cracking vessel is constantly augmented by the formation of carbon by cracking. However, if the latter source of supply makes too much carbon available, the excess carbon may be removed from the reaction system with the carbon eliminator housed in the filter case 15.

It will be apparent from the foregoing description that the cracking method of the present invention is a quite economical and eicient method, wherein what are needed merely comprise an initial supply of small amounts of carbon powder and the injection of a pulsating current to the electrodes immersed in the liquid hydrocarbon material to be cracked. The carbon needs not be replenished but reproduces itself, so to speak, to allow a series of spark discharges to take place continually and automatically.

A notable advantage of the cracking method of this invention is that, unlike the conventional thermal cracking methods, hydrocarbon materials may be effectively cracked at low temperatures. In other words, there is no fear of possible ignition and explosion. Moreover, the equipment required may be constructed at low cost. The last but not the least important, the cracking method of this invention is superior to any other known cracking process in respect of yield, for the product gas consists, for a large part, of such unsaturated hydrocarbons as acetylene, ethylene, propylene, and butylene as shown in Table l.

What I claim as my invention:

1. A process for cracking liquefied hydrocarbon materials into gaseous components by sparking discharge, comprising the steps of: producing a mixture of liquefied hydrocarbon material with microiine electrically conductive carbon particles being of a size of between about 0.1 to 0.01 mm. and said mixture being prepared in a ratio of about grams of carbon to 1,000 liters of hydrocarbon; containing said mixture in a reactor, equipped with a pair of electrodes; subsequently subjecting said mixture in said reactor to a pulsating current between the electrodes of a voltage sufficient to effect spark discharges among the carbon particles occurring with an accompanying noise and prior to the application of said current interposing the step of presetting said gap between said electrodes to prevent arc discharges when said pulsating current is applied, while maintaining the temperature of said mixture at between about 20 to 60 C. throughout the reaction.

2. A cracking process substantially as described in claim 1, wherein only the initial supply of said hydrocarbon material contains said carbon particles and liquid hydrocarbon material cracked is continuously admixed to replace the hydrocarbon material already cracked.

3. A cracking process substantially as described in claim 1 and including the step of filtering the mixture to remove excess carbon from the said reactor.

4. A cracking process substantially described in claim 1, wherein said electrodes are carbon rods.

5. A cracking process substantially as described in claim 1, wherein the gap between said electrodes is Ibetween about 50 to 150 millimeters.

5 6 6. A cracking process substantially described in claim 2,353,770 7/ 1944 Suits 204-171 1, wherein said pulsating current is about 3,000 to 100,000 2,799,640 7/ 1957 Pevere e1; al, 204,- 171 volts and about 20 to 100 kilocycles per second. 3,169,915 2/1965 Kennedy 204-171 7. A cracking process substantially as described in claim 5, said gap being about 50 mm. to 150 mrn. 5 ROBERT K MIHALEK, primary Examiner References Cited Us C1 X R UNITED STATES PATENTS I 3,220,873 11/1965 Wesley 204-171 204170172260679 3,225,252 12/1965 Schrom etal 315--121 l0 

